Liberation of Hydrogen Sulfide from Dicysteinyl Polysulfanes in Model Wine

Abstract

Diorganopolysulfanes can be generated when hydrogen sulfide (H2S) and thiols are oxidized in the presence of Cu­(II) under conditions usually aimed at removing H2S from wine. This work sought to understand if polysulfanes could act as latent sources of H2S during postbottling storage. The stability of the polysulfanes formed in situ in model wine containing cysteine, H2S, and transition metals was dependent both on the number of sulfur linking atoms (Sn) and on the presence of a reducing agent, such as sulfur dioxide or ascorbic acid. A polysulfane containing three linking sulfur atoms was the most stable, with 84% of the relative initial amount remaining in solution after six months, compared to polysulfanes containing four or more linking sulfur atoms that decomposed rapidly, with 26% remaining after six months. Importantly, sulfur dioxide was associated with the rapid degradation of polysulfanes and subsequent liberation of H2S. Three cysteine-S-sulfonates were also tentatively identified, which gives insight into the possible release mechanisms involved with H2S reappearance.

Copper(II) and Sulfur Dioxide in Chardonnay Juice and Shiraz Must: Impact on Volatile Aroma Compounds and Cu Forms in Wine

“…The addition of SO 2 to grape juice/must did not significantly (p ≤ 0.05) impact the total or free Cu concentration for either Chardonnay or Shiraz throughout the production process (Tables 1 and 2). SO 2 has been reported to lead to the degradation of polysulfanes to generate H 2 S [47], but in this study, the results did not reflect a significant (p ≤ 0.05) decrease in free Cu and increase in bound Cu for wines when the SO 2 was added prior to fermentation.…”

Electrochemical triggering of the Chardonnay wine metabolome

“…sulfonated adducts formed upon SO 2 addition at bottling only (0 g. hL -1 SO 2 added to the must) would be relatively more consumed after electro oxidation, than sulfonated adducts formed upon SO 2 addition both at pressing and bottling (8 g.hL -1 SO 2 added to the must). Our results thus shows that such thiol S-sulfonate adducts formed upon ageing (Arapitsas et al, 2016;Bekker, Kreitman, Jeffery, & Danilewicz, 2018) may contribute to the overall antioxidant resistance of wines.…”

Simplified measures of copper fractions in wine: colorimetric and filtration‐based approaches

“…One red wine with 0.8 mg/L total Cu did have free hydrogen sulfide just at the lower end of the aroma threshold range. If Cu addition to wine during production was inducing hydrogen sulfide precursors, such as polysulfanes (Bekker et al 2018), then these precursors were enabling only significant free hydrogen sulfide accumulation when the residual total Cu concentration was below 0.25 mg/L. Based on the results in Figure 1a, it would appear that the link between total Cu and increased hydrogen sulfide concentration during wine ageing (Ugliano et al 2011, Viviers et al 2013) cannot be automatically extrapolated to increased free hydrogen sulfide concentration in wine.…”

“…Extensive research has been conducted on the role of Cu during reductive ageing of wine (Bekker et al 2016, 2018, Vela et al 2017). The reductive character of wine is associated with the sensory detection of lower molecular mass sulfur compounds in wine for which hydrogen sulfide and methanethiol tend to be the dominant compounds (Smith et al 2015, Ferreira et al 2018, Kreitman et al 2019).…”

“…Many studies have shown that while Cu is added to wine by winemakers to remove sulfidic‐off odours, increased Cu addition to wine at bottling can lead to an increase in hydrogen sulfide concentration during wine ageing in many cases (Ugliano et al 2011, Viviers et al 2013, Vela et al 2017). Furthermore, the reaction between copper(II) and hydrogen sulfide in the presence of thiol compounds leads not only to copper(I) sulfide complexes but also to polysulfanes, which can be eventual precursors to hydrogen sulfide (Bekker et al 2018). A complication in the link between total Cu concentration in wine and volatile sulfur compounds is essentially the lack of information on the specific forms of both being measured in bottle trial experiments.…”